CVE-2025-20136Cisco Adaptive Security Appliance and Firepower Threat Defense Software Network Address Translation DNS Inspection Denial of Service Vulnerability

Description

A vulnerability in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.  This vulnerability is due to an infinite loop condition that occurs when a Cisco Secure ASA or Cisco Secure FTD device processes DNS packets with DNS inspection enabled and the device is configured for NAT44, NAT64, or NAT46. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static NAT rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to create an infinite loop and cause the device to reload, resulting in a DoS condition.

Timeline

Scores

EPSS (exploitation in 30 days)

0.66% · top 48% of all CVEs (13 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.6.

Affected products

• Cisco · Cisco Adaptive Security Appliance (ASA) Software

  • affected 9.12.3
  • affected 9.8.3
  • affected 9.12.1
  • affected 9.8.1
  • affected 9.12.2
  • affected 9.8.2.45
  • affected 9.8.2
  • affected 9.8.4
  • affected 9.14.1
  • affected 9.12.4
  • affected 9.8.2.26
  • affected 9.8.2.24
  • affected 9.8.2.15
  • affected 9.8.2.14
  • affected 9.8.2.35
  • affected 9.8.2.20
  • affected 9.8.2.8
  • affected 9.8.2.17
  • affected 9.8.2.28
  • affected 9.8.2.33
  • affected 9.8.2.38
  • affected 9.8.4.25
  • affected 9.12.3.2
  • affected 9.12.3.7
  • affected 9.8.3.18
  • affected 9.8.3.14
  • affected 9.8.4.15
  • affected 9.8.4.8
  • affected 9.8.1.7
  • affected 9.8.3.29
  • affected 9.14.1.10
  • affected 9.12.2.5
  • affected 9.8.4.22
  • affected 9.12.3.12
  • affected 9.8.4.7
  • affected 9.8.4.17
  • affected 9.8.3.16
  • affected 9.8.4.20
  • affected 9.8.3.11
  • affected 9.12.1.3
  • and 169 more

• Cisco · Cisco Firepower Threat Defense Software

  • affected 6.2.3.14
  • affected 6.4.0.1
  • affected 6.2.3.7
  • affected 6.2.3
  • affected 6.4.0.2
  • affected 6.2.3.9
  • affected 6.2.3.1
  • affected 6.2.3.2
  • affected 6.4.0.5
  • affected 6.2.3.10
  • affected 6.4.0
  • affected 6.4.0.3
  • affected 6.2.3.6
  • affected 6.4.0.4
  • affected 6.2.3.15
  • affected 6.2.3.5
  • affected 6.2.3.4
  • affected 6.2.3.3
  • affected 6.2.3.8
  • affected 6.4.0.6
  • affected 6.2.3.11
  • affected 6.2.3.12
  • affected 6.2.3.13
  • affected 6.4.0.7
  • affected 6.4.0.8
  • affected 6.6.0
  • affected 6.4.0.9
  • affected 6.2.3.16
  • affected 6.6.0.1
  • affected 6.6.1
  • affected 6.4.0.10
  • affected 6.4.0.11
  • affected 6.6.3
  • affected 6.6.4
  • affected 6.4.0.12
  • affected 7.0.0
  • affected 6.2.3.17
  • affected 7.0.0.1
  • affected 6.6.5
  • affected 7.0.1
  • and 51 more

What to do

Exploitation: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2025-24852 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2025-20136](https://cveledger.app/badge/CVE-2025-20136.svg)](https://cveledger.app/cve/CVE-2025-20136)

Record last updated 14 Aug 2025, 19:21 UTC.